Untersuchung des Haplotyp-abhängigen Milchdifferentialzellbildes, der Milchinhaltsstoffe sowie der Vaginaltemperatur in einem bovinen intramammären Infektionsmodell mit Escherichia coli und Staphylococcus aureus

Müller-Langhans, Katharina (2025): Untersuchung des Haplotyp-abhängigen Milchdifferentialzellbildes, der Milchinhaltsstoffe sowie der Vaginaltemperatur in einem bovinen intramammären Infektionsmodell mit Escherichia coli und Staphylococcus aureus. Dissertation, LMU München: Tierärztliche Fakultät

Abstract

Background: In dairy cattle, mastitis causes high financial losses and impairs animal well-being. Genetic selection is used to breed cows with reduced mastitis susceptibility. Techniques such as milk cell flow cytometry may improve early mastitis diagnosis. In a highly standardized in vivo infection model, 36 halfsib cows were selected for divergent paternal Bos taurus chromosome 18 haplotypes (Q vs. q) and challenged with Escherichia coli for 24 h or Staphylococcus aureus for 96 h after which the samples were analyzed in 12 h intervals. Vaginal temperature (VT) was recorded every three minutes. The objective of this study was to compare differential milk cell count (DMCC), milk parameters (fat %, protein %, lactose %, pH) and VT between favorable (Q) and unfavorable (q) haplotype cows using Bayesian models to evaluate their potential as improved early indicators of differential susceptibility to mastitis. Results: After S. aureus challenge, compared to the Q half-sibship cows, the milk of the q cows exhibited higher PMN levels according to the DMCC (24 h, p<0.001), a higher SCC (24 h, p<0.01 and 36 h, p<0.05), large cells (24 h, p<0.05) and more dead (36 h, p<0.001) and live cells (24 h, p<0.01). The protein % was greater in Q milk than in q milk at 0h (p=0.025). In the S.aureus group, Q cows had a greater protein % (60h, p=0.048) and fat % (84h, p=0.022) than q cows. Initially, the greater VT of S.aureus-challenged q cows (0 and 12-24h, p<0.05) reversed to a lower VT in q than in Q cows (48-60h, p<0.05). Additionally, the following findings emphasized the validity of the model: in the S.aureus group all DMCC subpopulations (24 h-96 h, p<0.001) and in the E.coli group nearly all DMCC subpopulations (12 h-24 h, p<0.001) were higher in challenged quarters than in unchallenged quarters. The lactose % was lower in the milk samples of E.coli-challenged quarters than in those of S.aureus-challenged quarters (24h, p<0.001). Between 12 and 18 h, the VT was greater in cows challenged with E.coli than in those challenged with S.aureus (3-h interval approach, p<0.001). Conclusion: This in vivo infection model confirmed specific differences between Q and q cows with respect to the DMCC, milk component analysis results and VT results after S.aureus inoculation, but not after E.coli challenge. However, compared with conventional milk cell analysis monitoring, e.g., the global SCC, the DMCC analysis did not provide refined phenotyping of the pathogen response.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: cattle, intramammary infection model, milk parameters, vaginal temperature, mastitis
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 590 Tiere (Zoologie)
• Fakultäten: Tierärztliche Fakultät
• Sprache der Hochschulschrift: Deutsch
• Datum der mündlichen Prüfung: 8. Februar 2025
• 1. Bericht­erstatter:in: Petzl, Wolfram